Yes you can lay paver and outdoor tiles over an existing
concrete. The concrete should in sound condition and not all broken. If it is
it’s better to remove it and start fresh.

With that said there are a few things to keep in mind.

Drainage is one of the big ones since the concrete will not
let the water soak into the ground. If the patio is slopped correctly than as
long as you don’t block the water from running off with any kind of boarder you
should be ok.

Another concern would be the height. The new pavers can be
up to 3” higher than the original concrete so it could interfere with
transitions to doors or other surrounding areas.

You will still need to put joint sand in the joints and also
some kind of edging to keep the pavers in place. **Just make sure not to block
the water from running off of the slab.**

I hope that answered your question. Let me know if you have
any other questions. I would love to help.